On 1 Feb 2006 16:39:05 -0800,
[email protected] wrote:
>why buy the "right" tube diameter when the next larger size provides
>greater flat protection due to the rubber getting stretched less thin-
>as buying a 38c not a 32c
>or is this faulty logic?
It's faulty logic. First, if the next larger is really too large, it
may wrinkle and fail. Second, if it's really enough thicker to be
resistant to punctures, then it'll also be enough thicker to increase
rolling resistance by itself. Third, a *properly sized* tube isn't
stretched all that thin. Fourth, if you want a thick tube, they exist
and are sold as "thorn resistant" for many sizes of tire, but they
carry the same rolling resistance penalty mentioned above. Fifth,
mere marked size range isn't likely to be a good guide for what you're
trying to find; see comments below.
>or to ask another way-how much weight is saved and speed gained from a
>38 to a 32?(x2)?
Not much, but there's not a lot of difference there.
If you sample the various brands of tube, you will find that there are
many tubes marked as usable across that size range (and beyond), for
one thing. If you collected tubes and measured their wall thickness,
you would probably also discover that some brands (and samples within
brands) of nominally same-size units vary considerably in both initial
and installed thickness, so that the mere marked size range might not
be a reliable indicator of whether a given tube will achieve the
result that you're seeking.
--
Typoes are a feature, not a bug.
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